dianad- so sorry for your loss. I've known several women (and men) in the same difficult position - it is so hard. And as you say, selling a property abroad can be a nightmare. Most expats have bought homes which were 'cheap' as compared to UK as they were in rural areas where the French just do not want to live (Dordogne, Auvergne, etc) - and the only prospective buyers are expats. With the concerns over Brexit, £ exchange rates and future accessibility to health care provisions - that market is very wobbly. A friend has been trying to sell a wonderful house in the St Emilion area- lots of interests by curious (nosy) people - but no offers!?!
Different for us, as after 40 years in UK, married to a Brit- we decided to move here, in French speaking Switzerland near French border- in retirement. Little did we know that the Swiss Franc would keep going up, and the £ tumble so quickly- and now nearly 60% less than when we moved here 8 years ago- and with a possible further 10 to 20% in the offing if Brexit goes belly up, and the UK with it- and the possibility of also losing reciprocal health care and have to pay huge sums for private health care (around £500 a month each). We have many friends here, we both speak French fluently, etc, - but if I ever was widowed- I would want to return to UK to be near daughters and grandchildren.